Save does not work. prompt() is not and will not be supported.
I'm looking into the problem still but I'm assuming it's something to do with the save name input and certain browsers. I'll probably disable this feature for now until someone gets back to me on how to resolve it (I'm still learning things x.x). If it persists then it's something else. Unfortunately, I can't be certain as I haven't personally had this error occur.
I already have an update planned to release later today or tomorrow (PDT). I'm still testing and going over it at the moment but I'll remove it then. Sorry for the inconvenience.